3" exhaust ?'s (1 Viewer)

[guenther65]

I am having a 3b installed into my 64' FJ-40 with plans of installing a turbo in the future. If I plan on going with a 3" exhaust when I turbo it, would it be better to go with 3" from the start?

Thanks,
Michael

 

[TurboDiesel69]

Absolutely!

 

[guenther65]

Would back pressure be an issue? I spoke with a tech at a muffler shop and he said that there could be.
Also, would I need the stock down pipe from the exhaust manifold? I need one, should I go with 3" from the manifold?

Thanks,

Michael

 

[gifu]

try not to laugh next time a muffler "tech" says backpressure is an issue on a diesel.
3" the entire length for sure.

 

[Tapage]

which turbo are you planning to run in your 3B ..? how much boost ..

3" isn't bad .. just maybe you don't need that much .. 2.5" would be plenty IMOP ..

 

[crushers]

jesus, 3" on a 3B?
give you head a shake and rethink your sizing. 3.4L engine with a max rpm of 4000 (on a really good day) pumping out MAYBE 150 hp if you crank the fuel and add an intercooler (maybe 175 if you add propane).
way over kill and a bugger to run. 2.5" is more than you will ever need, cheaper, easier and much more realistic
but
you do what ever turns your crank.

 

[gifu]

Wayne your are forgetting an important fact to figure into the equation: chicks dig it.
heh heh.

I ran 13BT with 3"... has a nice sound. About the same cost of 2.5". So, i figured, what the heck. Mas macho. no downside. and the women... oh man... no, not really.

 

[crushers]

chicky men dig it ...

seriously though, there is no downside to a larger than needed exhaust on a diesel, hell they will run fine with no exhaust at all.

 

[veggieguy]

Would back pressure be an issue? I spoke with a tech at a muffler shop and he said that there could be.
Also, would I need the stock down pipe from the exhaust manifold? I need one, should I go with 3" from the manifold?

I read somewhere that it's a good idea for a turbo'd diesel to use the stock downpipe from the manifold, and then start the larger diam. after that. Somehow it's a benefit for the smaller size coming directly off the mainfold? Can't remember where I saw that, though.

I'm installing a 3.1L 4cyl turbo diesel in an Isuzu Trooper and I plan to do this, with 2.5" pipe after the short downpipe. It will certainly be easier considering the limited space I have to work with.

 

[RufusTheDufus]

I've found this article a number of times doing web searches for turbo exhaust sizing. It's a response from a Garrett engineer about sizing exhausts with turbos. 3" is overkill, even 2.5" is overkill for a gas engine putting out the power that a 3B generates. (I don't know if a diesel produces more exhaust volume than a gasoline engine.)

With respect to using the stock downpipe size from a turbo I don't see any value it that. Turbos operate more efficiently with a large pressure differential. You want the least amount of resistance to exhaust flow at the turbine outlet. This will help your turbo spin up faster.

 

[TurboDiesel69]

3 inch sounds awesome... it's not much more, why not?

 

[Radd Cruisers]

I'd agree that 2.5" is more than enough, and it's easier to work with.

I put a 3" system on my HJ61 and it spools MUCH faster than with the stock system. Have yet to stretch its legs on the highway.


~John

 

[Hulsty]

I run a short 3'' system on my 13BT, does run 25psi boost though

 

[Tapage]

I run a short 3'' system on my 13BT, does run 25psi boost though

bet you can do the same with 2.5" .. but again I'm not against 3" ..